(A historic nor’easter produces major flooding on the U.S. East Coast even as a blizzard pounds the UK in early March. Were these extreme storms linked to human-caused climate change and related rapid polar warming? A new scientific study says — yes. Image source: NASA Worldview.)

A new study led by pioneers in the emerging field of climate change attribution for extreme weather events (including the notable Dr. Jennifer Francis), finds:

Recent boreal winters have exhibited a large-scale seesaw temperature pattern characterized by an unusually warm Arctic and cold continents… Using a recently developed index of severe winter weather, we show that the occurrence of severe winter weather in the United States is significantly related to anomalies in pan-Arctic geopotential heights and temperatures.

In particular, the authors discovered that “winter storms were two to four times more likely when the Arctic is abnormally warm, compared to when it was abnormally cold (emphasis added).”

(A new study in the journal Nature finds that winter storms in the U.S. are two to four times more likely when the Arctic is abnormally warm than when it is abnormally cold. Due to human-caused climate change, the Arctic is now warming up at a rate two times faster than the rest of the globe (emphasis added). Image source: Atmospheric and Environmental Research.)

With the new NASA global temperature data set out, I thought we’d take this opportunity to apply a bit of context to apparent stormy changes we see at present in winter weather patterns.

The first bit that I’d like to be crystal clear about is that the Arctic, overall, has become much, much warmer than usual during winter. That this warming spike occurs in the context overall global warming. And that this polar warming is increasingly associated with severe weather events in the middle latitudes and especially over the land and North Atlantic mid latitude zones.

The above graph shows polar temperature anomalies from the surface (1000 mb/2 meter) of the Earth to the top regions of the atmosphere (10 mb/25 kilometers). Along the bottom of the graph, we have a list of extreme weather events. Analyzing the graph we find that major polar warming associated with extreme temperature increases at the bottom of the atmosphere all the way through to the stratosphere correlate with recently more frequent historic blizzards and nor’easters in the regions mentioned.

(From January [top] to February [bottom] the pole heats up and extreme weather events ensue. Image source: NASA.)

But let’s take this analysis a step further to look at, as January progressed into February, where it got warmer, where it got colder, and where the big storms fired off.

The maps above show global temperature anomalies (NASA) for January (top) and February (bottom). And looking at those maps we find that the polar region heated up significantly from already warm ranges of 4 to 6.9 degrees Celsius above average during January to an amazing 4 to 12.3 C above average during February.

As this relative polar warming increased during February, the NASA maps show that colder than normal temperatures expanded over North America through Canada and parts of the Northern U.S. even as a cold spell began to blossom in Europe. Cold pools that were fed by Arctic air shunting southward as the Polar Vortex collapsed and remnant continental troughs emerged.

NASA’s zonal anomaly measures provide further evidence for this trend.

(Major northern polar warming from January [top] to February [bottom] is clearly visible in NASA’s zonal anomalies maps. Note that despite cold air excursions into North America and Europe, most zonal regions are warmer to much warmer than average.)

For here we find that as temperatures spiked from 4.5 degrees Celsius above average in the polar region of 80 to 90 degrees north latitude during January to an amazing 11 degrees above average during February, the region of 45 to 70 N dipped from 1 to 3 C warmer than average to 0.8 to 2.5 C warmer than average.

Note that the zonal middle latitude continental cooling is moderated by both the relatively warmer oceans and by very strong ridge zones running through these regions. But that the trough regions over both Europe and North America produced locally frigid temperatures and related instances of extreme weather.

Putting all these maps together from top to bottom we find that the polar warming events coincided both with mid latitude cooling even as we saw extreme snowfall in Canada and Montana, historic cold and snowfall in Europe and the UK, record flooding in the Central U.S., and record heat along the U.S. East Coast. We also find that the developing deep trough over Canada due to the expulsion of polar air southward in turn produced the succession of instabilities that would later spawn 3 very severe nor’easters off the U.S. East Coast during March.

Of course, all of these severe weather events are happening in the context of months that are around 1 degree Celsius warmer than 1880s averages globally. That January was the fifth hottest on record and that February was the sixth hottest on record during a La Nina that, all things being equal, should cause the world to be cooler than average.

But as we can see clearly here, all things are not equal — human-caused climate change is a big spoiler.

DJ

Every two weeks in Southern Alberta we’re being hit with heavy snowfall warnings and 20+ cm (8+ in) dumps of snow. Normally these would be a once-a-season event, winters here are cold but normally fairly dry. Weather forecasters haven’t adapted, consistently they forecast 1 – 5 cm until the day before the storm, then put out the last-minute snowfall warnings.

However, while it’s been abnormally, persistently cold here (I think we’re the only area in North America that hasn’t been experiencing any above normal temperatures through the winter) the actual ‘coldness’ is warmer than what would usually be counted as ‘cold’ here. Anecdotally, the coldest days this winter were about 10C (18F) warmer than what would have historically counted as ‘cold’.

Brian

There’s twenty inches of snow BECAUSE of the extra moisture loading that our messing with the atmosphere has enabled. Fifty years ago, there would have been maybe only fifteen or even ten inches. We are seeing moisture events that are at the same time more INTENSE but less FREQUENT. Humans can adapt to the immediate effects of this, but plants and animals (on which we rely for food) might not be so lucky.

“In the new research, Marilena Oltmanns and two colleagues at the GEOMAR Helmholtz Center for Ocean Research in Kiel, Germany, found that following particularly warm summers in the remote Irminger Sea, convection tended to be more impaired in winter. In some cases, a layer of meltwater stayed atop the ocean into the next year, rather than vanishing into its depths as part of the overturning circulation, which has sometimes been likened to an ocean “conveyor belt.””

There trend is certainly for more fresh water being released and less overturning circulation. I think this movement will be more clearly apparent over the next ten years. This will tend to produce some of the atmospheric feedbacks we’ve been concerned about. But I don’t think it really starts to ramp until the mid 2030s on the present track.

“Brock Long, whom President Donald Trump appointed to run FEMA last year, has equivocated on whether climate change is real and man-made. ‘The term climate change has become such a political hot button that, I think, I keeps us from having a real dialogue,’ he told Bloomberg in an interview last summer.”

Trump’s really stacked the deck with climate change deniers. It’s more notable when someone in his administration isn’t a denier. Of course, the majority of republicans in Congress also express denial related views. This is contrary to the vast majority of the American public.

canyonJack

And what’s wrong with Kansas (and Oklahoma)? Wichita: it’s the driest winter in nearly 100 years. http://www.kansas.com/news/weather/article205426754.html
“Dozens of wildfires burned thousands of acres across Kansas on Thursday, as strong winds and dry conditions continued to make the Sunflower State a massive tinder box.

The threat for more fires will only increase on Friday, weather officials say, with ‘catastrophic’ conditions in place thanks to temperatures in the 70s and winds that will top 40 miles an hour at times.

The National Weather Service has issued a red flag warning from Friday morning in through the evening in parts of eastern Kansas and all afternoon and early evening in all of southeast Kansas. A total of 36 counties are in the warning zone, including the Wichita metropolitan area.

State officials tracked 45 fires across the state on Thursday alone, with several of them breaking out in the Kansas City area. The fires burned an estimated 13,000 acres, and many remained active or out of control…The only part of Kansas that is not suffering from drought or at least abnormal dryness is a snippet in the northwest corner of the state, according to the U.S. Drought Monitor report released Thursday.

Nearly 20 percent of the state is enduring either exceptional or extreme drought…”

Another Wichita Eagle article titled “Tuesday’s winds across Kansas rivaled hurricanes and tornadoes”: “They were strong gusts, though, routinely topping 60 miles an hour around the Sunflower State. A gust of 73 miles an hour north of Scott City was one mile short of matching hurricane winds, according to the National Weather Service.”

If you take a look today at ClimateReanalyzer, the nation’s hot spot centers very dark red over Kansas.

The ridge/warm zone has shifted toward the Central U.S. The extra heat is promoting extreme drought and fire danger during March. We’ve had big fires before there during this time of year. But climate change is an amplifier.

bobinspain

The weather’s all over the place here in Spain. Variations on a theme of hot, cold, windy, rainy. From one day to the next. Very unstable. And now, as temperatures looked like they were about to start going up, we’ve another cold front sweeping in. It’s what we’d expect, I guess, with a whacky Jet Stream. What’s next? Who knows. One can only logically foresee even wilder conditions, I suppose, given the trends.
It ain’t just gonna suddenly sort it self out.
If only these blasted winds would just stop!http://www.lavanguardia.com/vida/20180316/441557322543/frio-siberiano-nueva-ola-espana.html

Dave McGinnis

Another great write-up Robert, a good summary. I once had the idea that northeast storms delivered the snow to Labrador that became the source region for the continental ice sheets — everything moved away from there.